1. Field of the Invention
The present invention relates to a semiconductor device having a capacitor.
2. Description of the Related Art
In recent years, a ferroelectric memory using a ferroelectric film as a capacitor dielectric film, that is, FeRAM (Ferroelectric Random Access Memory) has been developed.
A signal charge stored in a capacitor usually depends on the capacitor area. For this reason, if the capacitor occupied area decreases with high integration of the ferroelectric memory, it is difficult to store sufficient signal charge in the capacitor. Therefore, it is important to improve capacitor characteristics, and thereby increase charge stored per capacitor unit area.
The following proposal has been made as a conventional technique in JPN. PAT. APPLN. KOKAI Publication No. 7-193137. According to the proposal, the side portion of the capacitor is used to increase capacitance. However, even if the side portion of the capacitor is used, the capacitor characteristics do not so improve; therefore, it is difficult to essentially solve the problem.
As described above, it is conventionally difficult to improve the capacitor characteristics, and thereby increase the charge stored in the capacitor.